Renewable Farming

How RTK can cut costs by precision placement of nutrients, biologicals

One of our WakeUP clients plans to use his self-propelled sprayer’s Real Time Kinematic (RTK) guidance system to apply two focused streams of liquid fertilizer, biologicals and WakeUP Spring after planting corn, but before the corn emerges. One stream will pinpoint two inches left of the row, the second stream two inches right of the row.

It’s an alternative for in-furrow placement with the planter, which is one of our favorite application methods to focus nutrients where (and when) they’re most effective.

March 6, 2018 — Before RTK technology, it would be impossible to guide a high-clearance Hagie or Miller with a 120-foot boom so precisely that each nozzle pinpoints a tiny, solid stream two inches from the row. But development of less expensive RTK systems and sophisticated spray boom controls make positioning within an inch possible. Earlier RTK systems accelerated strip-till placement of fertilizer by enabling planters to precisely track the planter furrow directly over the fertilizer band. Now, the same precision looks able to place smaller amounts of nutrients and biologicals precisely, even before the first spikes of corn emerge.

Inoculation of the root zone with beneficial mycorrhiza and other microbes applied on the soil surface might be almost as effective as in-furrow placement. And it’s a bit more “forgiving” if you want to increase your fertilizer rates. One or two rainfalls, and the nutrients and biologicals will probably percolate into the root zone.

Many row-crop farmers who own larger planters don’t want to install in-furrow application tanks, pumps and tubes on an already complex planter. Nor do they want to slow down a big central-hopper planter for refills with liquids. But a separate field trip with a 1,000-gallon tank on a wide-boom GPS/RTK sprayer can cover acreage fast. It also allows a second operator to make that pop-up fertility/biological pass while the planter is still rolling on another field. Wind speed isn’t much of an issue with this application, because the liquid delivery is in a thin, smooth stream under pressure. Kind of an “injection.”

Corn at V2 stage, ideal for applying WakeUP Spring

After this premerge pass, the grower can then switch his RTK-equipped sprayer to fan tips, and follow up with another mission when corn is at the V2 (two leaf) stage: Spraying a tight band of WakeUP Spring and additional nutrients and biostimulants directly over young corn. (This was the original use of WakeUP a decade ago. It does enhance massive roots. But many farmers worried that “there’s just not much to spray, it’s mostly wasted” when they sprayed with a broadcast application.) 

After the corn is tall enough to guide Y-drop fertilizer application systems, the same sprayer can follow the same track to pump out heavier rates of stabilized nitrogen and other nutrients as indicated by tissue tests or early-spring soil N tests. The Y-drop again puts liquids on both sides of the row, and near the row.

Newer sprayers also offer precise boom height control, using radar or gyro systems. The Horsch 330 introduced in 2016 has a gyro-stabilized boom which keeps boom wings at a steady height above the ground, plus sensors which raise it above field obstacles. Earlier we showed a 4-minute YouTube video of that sprayer; it’s at this link.  One of our WakeUP clients, Windy Lane Farms in Indiana, is a U.S. distributor for Horsch, a German firm.

Spoon-feeding fertility when needed, and where needed, can also greatly reduce NPK pollution in tile lines and downstream. Corn growers who unleash soil biology and place nitrogen within easy reach of a mycorrhizal-rich root can raise 200-plus bushel yields with less than a half-unit of applied N per bushel. 

The latest advisory from Iowa crop consultant Bob Streit underscores that idea: “More growers recognize that applying most or all of their N six months before the corn crop needs it allows too much time for it to be lost. We have seen the development, patenting and marketing of the Y-drops offer a great tool to help farmers apply the N closer to the time of crop uptake. Also, the use of calcium, sulfur, carbon or molasses based stabilizers seems to be on the increase. The acreage of branded stabilizers is also increasing, and we see decisions about which ones to use may come down to which are the least damaging to soil biology.”